I found some answer as We can put our spouses in our tax return documents.can any body explain a little bit.thanks

Foreign students on the F-1 visa CAN claim their spouse on the non-resident return (Form 1040NR) if they are from Canada, Mexico, India or South Korea.

Otherwise, the spouse CANNOT be claimed on the return unless the person filing is a resident alien, green card hoklder or U.S. citizen.

Thanks,
Is it only those countries are eligible?what about other south Asian countries?

Is it only those countries are eligible?what about other south Asian countries

On F-1 you are nonresident for 5 years. Non residents can not claim dependents except Canada and Mexico and if provided by tax treaty between the country and U.S.
No other south Asian country has this provision. Your U.S. Tax Return: U.S. Tax Filing Requirements for Non-Residents (http://taxipay.blogspot.com/2008/03/us-tax-filing-requirements-for-non.html)

Yes.

U.S. tax law specify that countries with whom the U.S. shares a border allows the wife and children of foreign nationals from Canada and Mexico to be claimed.

South Korea and India negotiated this issue when the tax treaty was signed.